Photoelectrochemical Technology Research Articles

Vertically‐Aligned GaS Nanosheets‐Based Photoelectrochemical Photodetector for Fast‐Speed, High‐Sensitivity, and Self‐Powered UV–vis Underwater Optical Communication

AbstractUnderwater optical communication (UOC) based on the novel photoelectrochemical (PEC) type photodetector has garnered substantial interest in the field of marine resource exploration and ocean investigation due to its strong operability, self‐powered capability, and large sensitive area in harsh underwater environments. To achieve high sensitivity, fast transmission speed, and broadband response characteristics, vertical‐GaS nanosheets‐based PEC photodetectors are prepared by chemical vapor deposition for UOC application. The GaS based PEC photodetector exhibits excellent self‐powered photodetection and a broad UV–vis photoresponse range as well as high stability performance in both Na2SO4 electrolyte and seawater. Notably, it also demonstrates an exceptional photoresponsivity of 11 mA W−1 coupled with a fast response and recovery time of 12.9 and 13 µs which are superior to those of 2D layered materials and conventional wide‐bandgap semiconductors. These improvements are mainly due to the large surface area, short diffusion length, as well as high carrier mobility of vertically‐oriented GaS nanosheets. Strikingly, the constructed GaS photodetector showcases a broad bandwidth exceeding the −3 dB cutoff frequency of 55.3 kHz during UOC testing, successfully enabling transmission and decoding of character information. This work establishes the groundwork for developing high‐performance, self‐powered UV–vis photodetectors adaptable to UOC using PEC technology.

Photoelectron-transfer-effect grafting: Validation of a generalized strategy for fluorescence and photoelectrochemical dual-mode detection of hydrogen sulfide

BackgroundThe progress of modern research is constantly fueled by the convergence of multiple technologies. Despite the enormous potential of both fluorescence (FL) and photoelectrochemical (PEC) technologies, the development of synergistic PEC-FL sensing platforms that combine the advantages of both is still in its early stages due to their relatively recent inception. Hydrogen sulfide (H2S), possessing dual irritant and asphyxiating traits, poses challenges for environmental preservation and human health. The development of the PEC-FL detection methodology for H2S in complex environmental settings is imperative. ResultsCombining FL and PEC sensing techniques, this work presented a new concept of photoinduced electron-transfer (PET) effect grafting for dual-mode fluorescence and PEC analysis. Briefly, a well-designed fluorescent molecule (BTFM-DNP) featuring the PET effect was synthesized and implemented to modulate the photoelectric response of the indium tin oxide (ITO)/BiOI photocathode electrode. After reacting with H2S, the thiolysis of dinitrophenyl ether eliminated the intramolecular PET effect and recovered the significant fluorescence of the probe. Remarkably, the newly formed 2,4-dinitrobenzenethiol (DBT) with strong electron-withdrawing groups was then grafted to the ITO/BiOI photoelectrode and achieved the successful transfer of the PET process, resulting in a sharp decrease in photocurrent. The as-developed dual-mode protocol exhibited good performance in terms of ultra-sensitivity, high selectivity, fast response, and a wide detection range from 1 pM to 80 μM. SignificanceThe newly developed PEC-FL sensing platform can be applied to detect H2S levels in both the environment and food. This study demonstrates a promising synergy between fluorescent probes and PEC sensors, offering a novel perspective on the advancement of multi-mode analysis techniques. This approach has the potential to significantly enhance detection accuracy and reliability.

Visible-light-prompted photoelectrochemical sensors fabricated using Er3NbO7/P@g-C3N4/SnS2 nanocomposite for detecting mercury ion in environmental water samples

Photoelectrochemical (PEC) detection technology is key for fighting pollution, leveraging the photoelectric conversion of the photoelectrode material. A specialized photoelectrode was developed to detect Hg2+ ions with exceptional sensitivity, utilizing an anodic PEC sensor composed of Er3NbO7/P@g-C3N4/SnS2 ternary nanocomposite. Rare earth metal niobates (RENs) were chosen due to their underexplored potential, whose performance was enhanced through bandgap engineering and surface modification, facilitated by P@g-C3N4 as an immobilization matrix and SnS2, belonging to the I-IV semiconductors category fostering hybrid heterojunction formation for boasting optical properties and suitable redox potentials. Introducing Hg2+ into the system, a specific amalgamation reaction occurs between reduced Hg and Sn. This reaction obstructs electron transfer to the FTO electrode surface, leading to the recombination of charges. The proposed PEC sensor exhibited remarkable analytical performance for Hg2+ detection, high sensitivity, a detection limit of 0.019 pM, excellent selectivity, and a detectable concentration range of 0.002–0.15 nM. Additionally, it demonstrated good recovery and low relative standard deviation when analyzing Hg2+ in water samples, highlighting the potential application of the heterostructure in detecting heavy metal ions via PEC technology.

Photoelectrocatalytic Hydrogen Generation: Current Advances in Materials and Operando Characterization.

Photoelectrochemical (PEC) hydrogen generation is a promising technology for green hydrogen production yet faces difficulties in achieving stability and efficiency. The scientific community is pushing toward the development of new electrode materials and a better understanding of the underlying reactions and degradation mechanisms. Advances in photocatalytic materials are being pursued through the development of heterojunctions, tailored crystal nanostructures, doping, and modification of solid-solid and solid-electrolyte interfaces. Operando and in situ techniques are utilized to deconvolute the charge transfer mechanisms and degradation pathways. In this review, both materials development and Operando characterization are covered for advancing PEC technologies. The recent advances made in the PEC materials are first reviewed including the applied improvement strategies for transition metal oxides, nitrites, chalcogenides, Si, and group III-V semiconductor materials. The efficiency, stability, scalability, and electrical conductivity of the aforementioned materials along with the improvement strategies are compared. Next, the Operando characterization methods and cite selected studies applied for PEC electrodes are described. Operando studies are very successful in elucidating the reaction mechanisms, degradation pathways, and charge transfer phenomena in PEC electrodes. Finally, the standing challenges and the potential opportunities are discussed by providing recommendations for designing more efficient and electrochemically stable PEC electrodes.

A Visible-Light-Driven Self-Powered Nodularin-R Biosensing Platform Controlled by an Integrated Portable Photoelectrochemical Detection Device.

The presence of nodularin-R (NOD-R) in water has gained considerable attention because of its widespread distribution and high toxicity. In this study, an accurate and rapid visible-light-driven self-powered photoelectrochemical (PEC) biosensor was developed by integrating a portable paper-based electrode with a custom-built miniaturized PEC detection device. The newly designed system successfully achieved on-site detection of NOD-R in real water samples based on PEC technology. First, target recognition triggers the initiation of the hybridization chain reaction to generate double-stranded DNA. The thus-formed double-stranded DNA entrapped methylene blue (MB), and the dye molecules were irradiated with visible light for conversion to leuco-MB in the presence of ascorbic acid. The resulting leuco-MB species significantly amplified the PEC signal output of TiO2-MXene, enabling NOD-R detection. Under optimal conditions, the proposed PEC assay strategy demonstrated NOD-R detection within a concentration range from 20 fg mL-1 to 10 ng mL-1 with a detection limit of 19.6 fg mL-1. In addition, a custom-built miniaturized PEC detection device conveniently integrates the detection component with the light source, enabling the real-time collection of results via a wireless module. This innovative self-powered PEC platform provides significant advancements in smooth and intelligent detection compared to traditional PEC detection devices.

Photoelectrochemical catalytic CO2 reduction enhanced by In-doped GaN and combined with vibration energy harvester driving CO2 reduction

Photoelectrochemical (PEC) technology seamlessly integrates and optimizes the merits of photocatalysis and electrocatalysis, facilitating charge separation and enhancing solar conversion efficiency. It stands out as a promising approach for CO2 treatment. GaN as III-Ⅴ semiconductor, has garnered substantial attention in the realm of PEC CO2 reduction reactions (RR). In this study, GaN and In/GaN micro-rods were prepared via straightforward hydrothermal synthesis. Attaining a current density of approximately 10 mA/cm2 and CO Faradaic Efficiency (FE) of ∼45 % at −0.75 VRHE (Reversible Hydrogen Electrode, RHE), In/GaN exhibited exceptional stability over a 2 h PEC CO2 RR. The introduction of In into GaN significantly augmented CO2 adsorption capacity and light harvesting. Additionally, Density Functional Theory (DFT) calculations elucidated that In-doped GaN can diminish the adsorption of intermediate CO, favoring subsequent CO desorption. Furthermore, the N-vacancy increased with In doping, resulting in a rise in the number of unpaired electrons, facilitating carrier transport. Herein, vibration energy harvester was introduced to drive CO2 RR, marking a significant advancement in development of PEC CO2 RR for future green energy applications.

Influence of solution pH dependency on structure, optical with photoelectrochemical characteristics of SILAR deposited copper oxide thin films

Photoelectrochemical (PEC) technology is a promising approach for converting solar energy into chemical energy, offering significant potential for renewable energy applications. In this work, the CuO thin film was fabricated with different pH value in between 8.5 ± 0.1 and 10.5 ± 0.1 via Successive Ionic Layer Adsorption and Reaction (SILAR) method. The Effect of pH on thickness, structural, morphological, elemental composition and optical properties were investigated by using stylus profilometry, XRD, SEM, TEM, EDX, UV–vis and PL. The XRD results showed that as the pH increased, the crystallite size increased from 19.24 nm to 25.62 nm, with a monoclinic phase along the (111) direction. The CuO film deposited at pH value 10.5 ± 0.1 exhibit well defined identical particle with its size in the range between 200 and 300 nm was confirmed by SEM and TEM analysis. As the pH increased from 8.5 ± 0.1 to 10.5 ± 0.1, the CuO film bandgap (Eg) value reduced from 1.52 eV to 1.42 eV with indirect transition. The CuO photocathode deposited at pH 10.5 ± 0.1 shows maximum photocurrent density of 1.45 mA/cm2 at −0.1 V vs. RHE in 0.5 M Na2SO4 solution. Furthermore, the Electrochemical Impedance Spectroscopy (EIS) analysis shows, the CuO (pH 10.5 ± 0.1) electrode have higher conductivity value of 0.6862 S/cm compared CuO at pH 8.5 ± 0.1 (0.2779 S/cm) and CuO at pH 9.5 ± 0.1 (0.4646 S/cm) electrodes.

Porous two-dimensional CuSe@BiOI isotype heterojunction with highly exposed (1 0 2) facets for efficient photoelectrocatalytic CO2 reduction and photodetection

Using photoelectrochemical technology to construct efficient photoelectric materials has aroused extensive research interest. In this study, we propose a two-dimensional porous CuSe@BiOI isotype heterojunction photocathode for CO2 reduction to formic acid. The heterojunction was constructed by the epitaxial growth of high-quality oriented BiOI nanosheets onto the porous CuSe framework. The CuSe framework as a template to ensure the formation of the (102) facets of BiOI and the isotropic charge transport characteristics of the (102) surface greatly improve the efficiency of charge separation and transfer. This CuSe@BiOI isotype heterojunction electrode can efficiently reduce CO2 to formic acid with a selectivity of up to 80.5 % in 0.5 M potassium bicarbonate aqueous solution. Meanwhile,the performance of the photodetector based on CuSe@BiOI heterostructure is 6.97 × 1011 Jones and a response rate of 87.13 mA W−1. This finding provides a new approach to designing stable heterojunction photoelectrocatalysts with isotropy.

Integrating detection and degradation of bisphenol A by photocatalytic fuel cell-driven photoelectrochemical sensor

To ensure food safety and environmental protection, it is crucial to rapidly identify and remove bisphenol A (BPA), a plasticizer commonly used in the inner lining of food containers and beverage packaging. Here, a photocatalytic fuel cell (PFC)-integrated self-powered photoelectrochemical (PEC) sensor is constructed. Unlike conventional single PEC or PFC sensors, this PFC-integrated PEC sensor relies on not only the difference in Fermi energy levels between photoanode and photocathode but also charge accumulation resulted from the oxidation of BPA by photogenerated holes. Consequently, this sensor achieved a remarkable maximum output power (Pmax) of 8.58 μW cm−2, as well as a high sensitivity, wide linear detection range (0.1–200 μM), low detection limit (0.05 μM), great stability, reproducibility, and real sample detection capability. This work integrates PFC and PEC technologies successfully for the rapid identification and efficient removal of BPA.

Integration of functional modules in a unified photoelectrochemical device for highly efficient solar-driven cathodic metal protection

The ever-increasing energy consumption stimulated the development of various solar energy conversion systems. Photocathodic protection (PCP), emerges as a promising photoelectrochemical technology to alleviate metal corrosion, but the centralization of all core reaction steps on one photoelectric-conversion-unit induces extremely low energy conversion efficiencies. Herein, a proof-of-concept modular PCP device incorporating electron transport layer (ETL), photoelectric conversion layer (PCL), hole transport layer (HTL) and hole consumption layer (HCL) is fabricated to delocalize the key reaction steps for the first time. Such a unified ETL/PCL/HTL/HCL architecture facilitates the efficient extraction of photoexcited electrons from the small-gap PCL to the protected metal through ETL, and holes to HCL for water oxidization through HTL. The directional “macroscopic” charge migration, prolonged charge lifetime and accelerated water oxidation lead to significantly improved PCP effectiveness in simulated seawater. Our findings provide a groundbreaking PCP design, allowing fine-tuning individual functional modules and inter-modular interfaces to vastly elevate performance.

Photoelectrochemical Conversion of Methane to Ethane and Hydrogen under Visible Light Using Functionalized Tungsten Trioxide Photoanodes with Proton Exchange Membrane.

Developing methane utilization technologies is desired to convert abundant and renewable carbon resources, such as natural gas and biogas, into value-added chemical products. This study provides insights into emerging photoelectrochemical (PEC) technology for the photocatalytic transformation of methane to C2H6 and H2 using visible light at room temperature. The PEC conversion of methane to oxygenates has been investigated in aqueous electrolytes. Herein, we demonstrate the gas-phase PEC methane conversion using a proton exchange membrane (PEM) as a solid polymer electrolyte and a gas-diffusion photoanode for methane oxidation. Tungsten trioxide (WO3), a semiconductor photocatalyst responsive to visible light, is utilized as the photoanode material. Ultraviolet light (∼365 nm) excitation predominantly results in CO2 production with lower C2H6 selectivity in humidified methane. In contrast, visible light (∼453 nm) effectively promotes C2H6 production over the WO3 photoanode, attributed to preferential hydroxyl radical (•OH) formation compared to UV irradiation. Photogenerated holes formed near the valence band maximum of WO3 contribute to •OH formation through a single-electron water oxidation. The photogenerated •OH activates gaseous methane molecules to methyl radicals, subsequently coupled into C2H6 at the gas-electrolyte-semiconductor boundary. H2 is concurrently formed on the cathode electrocatalyst. Improving the selectivity for the dehydrogenative coupling of methane is pivotal for enhancing the energy efficiency in the PEM-PEC system.

Twisted leaf like ZnO-flake-like BiOI@CNF grown on ITO substrate as a nanostructured pioneering platform for photoelectrochemical water splitting

Despite ZnO nanostructures garnering significant attention for photoelectrochemical (PEC) water splitting, the quest for efficient ZnO-based photoelectrodes with optimal light absorption, effective electron-hole separation, and transfer remains a challenge. The formation of ZnO heterojunctions with lower bandgap nanostructures of semiconductors has emerged as a strategy to enhance charge transfer while mitigating recombination rates. Additionally, the introduction of carbon nanofibers (CNFs) to these heterojunctions serves to further suppress recombination by electron trapping and enhances catalytic active sites, thereby elevating PEC performance. In this study, twisted leaf-like ZnO, flake-like BiOI, ZnO-BiOI nanostructure heterojunctions, and ZnO-BiOI@C composites were synthesized through a solvothermal method. Notably, the ZnO-BiOI@C photoelectrode exhibited outstanding performance, achieving a photocurrent density of 5.6 mA/cm2 through linear sweep voltammetry under light illumination. Each synthesized photoelectrode demonstrated robust photocurrent responsiveness and excellent stability under chopped conditions for up to 1150 s with a 50 s interval. This remarkable stability is attributed to the unique and stable morphological characteristics and strong crystallinity of the synthesized materials. The formed heterojunction between ZnO-BiOI was found to extend light absorption capabilities, while the incorporation of CNFs effectively trapped electrons from the heterojunction's conduction band, enhancing overall water splitting performance. The results underscore the potential of the ZnO-BiOI@C composite as a high-performing photoelectrode for PEC applications, emphasizing the importance of morphological and compositional considerations in advancing PEC technologies.

Frontiers in Photoelectrochemical Catalysis: A Focus on Valuable Product Synthesis.

Photoelectrochemical (PEC) catalysis provides the most promising avenue for producing value-added chemicals and consumables from renewable precursors. Over the last decades, PEC catalysis, including reduction of renewable feedstock, oxidation of organics, and activation and functionalization of C─C and C─H bonds, are extensively investigated, opening new opportunities for employing the technology in upgrading readily available resources. However, several challenges still remain unsolved, hindering the commercialization of the process. This review offers an overview of PEC catalysis targeted at the synthesis of high-value chemicals from sustainable precursors. First, the fundamentals of evaluating PEC reactions in the context of value-added product synthesis at both anode and cathode are recalled. Then, the common photoelectrode fabrication methods that have been employed to produce thin-film photoelectrodes are highlighted. Next, the advancements are systematically reviewed and discussed in the PEC conversion of various feedstocks to produce highly valued chemicals. Finally, the challenges and prospects in the field are presented. This review aims at facilitating further development of PEC technology for upgrading several renewable precursors to value-added products and other pharmaceuticals.

Photoelectrochemical CO2 reduction with copper-based photocathodes

The excessive consumption of fossil fuels has led to a rapid surge in atmospheric CO2 concentration, triggering severe energy crises and environmental concerns. In this context, photoelectrochemical (PEC) technology for CO2 reduction is perceived as a highly appealing resolution, due to its integration of the advantages offered by both photocatalysis and electrocatalysis. Undoubtedly, the photocathode plays a pivotal role within the PEC CO2 reduction system. Among various catalysts, copper (Cu)-based photocathodes have garnered significant attention owing to their low toxicity, affordability, advantageous band gap and distinctive active sites that enable the conversion of CO2 into a diversity of reduction products including carbon monoxide (CO), formic acid (HCOOH), methane (CH4), ethylene (C2H4), ethanol (C2H5OH) and so on. This review primarily delves into the current developments of Cu-based photocathodes in PEC CO2 reduction, encompassing aspects like material fabrication processes and modification techniques. Subsequently, an analysis is presented regarding the reaction mechanisms underlying different CO2 conversion products. Finally, an anticipatory perspective is provided regarding future research in the field of PEC CO2 reduction. This review enables researchers to promptly capture the latest advancements of Cu-based photocathode for PEC CO2 reduction, offers valuable insights for future research on the design and synthesis of Cu-based photocathode, and provides a guideline to achieve enhanced improvements in PEC CO2 conversion.

Review on synthetic approaches and PEC activity performance of bismuth binary and mixed-anion compounds for potential applications in marine engineering.

Photoelectrochemical (PEC) technology in marine engineering holds significant importance due to its potential to address various challenges in the marine environment. Currently, PEC-type applications in marine engineering offer numerous benefits, including sustainable energy generation, water desalination and treatment, photodetection, and communication. Finding novel efficient photoresponse semiconductors is of great significance for the development of PEC-type techniques in the marine space. Bismuth-based semiconductor materials possess suitable and tunable bandgap structures, high carrier mobility, low toxicity, and strong oxidation capacity, which gives them great potential for PEC-type applications in marine engineering. In this paper, the structure and properties of bismuth binary and mixed-anion semiconductors have been reviewed. Meanwhile, the recent progress and synthetic approaches were discussed from the point of view of the application prospects. Finally, the issues and challenges of bismuth binary and mixed-anion semiconductors in PEC-type photodetection and hydrogen generation are analyzed. Thus, this perspective will not only stimulate the further investigation and application of bismuth binary and mixed-anion semiconductors in marine engineering but also help related practitioners understand the recent progress and potential applications of bismuth binary and mixed-anion compounds.

Synergistic effect of Ag@CN with BiVO4 in a unique Z-type heterojunction for enhancing photoelectrochemical water splitting performance.

In the realm of photoelectrochemical technology, the enhancement of photogenerated charge carrier separation is pivotal for the advancement of energy conversion performance. Carbon nitride (CN) is established as a photocatalytic material with significant potential and exhibits unique advantages in addressing the issue of rapid recombination of photogenerated carriers. This study utilized an efficient in situ doping method that combined Mo,W-doped BiVO4 (Mo,W:BVO) with silver-loaded CN (Ag@CN), yielding an all-solid-state Mo,W:BVO/Ag@CN heterostructure that effectively augments the separation efficiency of electron-hole pairs. Through the annealing process, Ag@CN was uniformly coated within the Mo,W:BVO thin film, significantly enlarging the interface contact area to enhance visible light absorption and photogenerated carrier movement. The results of the photoelectrochemical tests showed that the Mo,W:BVO/Ag@CN heterostructure had the highest photocurrent and charge transfer efficiency, which were 6.4 times and 3.6 times higher respectively than those of the unmodified Mo,W:BVO. Our research elucidates the interactions within all-solid-state Z-scheme heterojunctions, outlining strategic approaches for crafting innovative and superior photocatalytic systems.

Emergent CuWO4 Photoanodes for Solar Fuel Production: Recent Progress and Perspectives

Solar fuel production using a photoelectrochemical (PEC) cell is considered as an effective solution to address the climate change caused by CO2 emissions, as well as the ever-growing global demand for energy. Like all other solar energy utilization technologies, the PEC cell requires a light absorber that can efficiently convert photons into charge carriers, which are eventually converted into chemical energy. The light absorber used as a photoelectrode determines the most important factors for PEC technology—efficiency, stability, and the cost of the system. Despite intensive research in the last two decades, there is no ideal material that satisfies all these criteria to the level that makes this technology practical. Thus, further exploration and development of the photoelectode materials are necessary, especially by finding a new promising semiconductor material with a suitable band gap and photoelectronic properties. CuWO4 (n-type, Eg = 2.3 eV) is one of those emerging materials that has favorable intrinsic properties for photo(electro)catalytic water oxidation, yet it has been receiving less attention than it deserves. Nonetheless, valuable pioneering studies have been reported for this material, proving its potential to become a significant option as a photoanode material for PEC cells. Herein, we review recent progress of CuWO4-based photoelectrodes; discuss the material’s optoelectronic properties, synthesis methods, and PEC characteristics; and finally provide perspective of its applications as a photoelectrode for PEC solar fuel production.

(Invited) An Artificial Leaf with a Solar-to-H2O2 Conversion Efficiency

Millions of families around the world remain vulnerable to water scarcity and have no access to drinking water. Advanced oxidation processes (AOPs) are an effective way towards water purification with qualified reactive oxygen species (ROSs) while are impeded by the high-cost and tedious process in either input of consumable reagent, production of ROS, and the pre-treatment of supporting electrolyte. Herein, we couple solar light-assisted H2O2 production from water and photo-Fenton-like reactions into a self-cyclable system by using an artificial leaf, achieving an unassisted H2O2 production rate of 0.77 μmol/(min·cm2) under 1 Sun AM 1.5 illumination. Furthermore, a large (70 cm2) artificial leaf was used for an unassisted solar-driven bicarbonate-activated hydrogen peroxide (BAP) system with recycled catalysts for real-time wastewater purification with requirements for only water, oxygen and sunlight. This demonstration highlights the feasibility and scalability of photoelectrochemical technology for decentralized environmental governance applications from laboratory benchtops to industry.

Defective Photocathode: Fundamentals, Construction, and Catalytic Energy Conversion

AbstractThe development of a long‐term and sustainable energy economy is one of the most significant technological challenges facing humanity. Photoelectrochemical (PEC) technology is considered as the most attractive route for converting solar energy into chemical energy. However, the slow reaction kinetics of PEC oxidation and reduction greatly hinder its practical application. To address this issue, engineering photoelectrodes with various defects can significantly improve their catalytic performance, which can not only regulate catalyst electronic structure but also promote charge transfer/separation by serving as an active/adsorption/energy storage site. Herein, the defect engineering strategies for photoelectrodes are systematically summarized, focusing on the latest progress in defective photocathode for energy conversion. First, an overview of defect types, basic principles of photocathode, and the positive role of defects in the photocathode are provided. Second, the construction strategies and characterization methods of defective photocathode are summarized. Then, the progress of typical energy conversion applications, including hydrogen production, CO2 reduction, and nitrogen reduction over defective photocathode, is reviewed, highlighting the crucial role of defects in high catalytic performance. Finally, the challenges and future prospects of defective photocathode are discussed, aiming to bring new opportunities for the development of photocathode through defect engineering.

A Synergic Effect of Bi-metallic Layered Hydro-Oxide Cocatalyst on 1-D TiO2 Driven Photoelectrochemical Water Splitting

ABSTRACT Photoelectrochemical (PEC) water splitting is one of the most sustainable approaches for converting solar energy into hydrogen fuel. Affordable and robust photoelectrodes are crucial for the commercialization of PEC technologies. Recently, transition metal-based co-catalysts, especially Ni- and Fe-based catalysts, have attracted much interest owing to their exceptional OER characteristics. Given this, we here proposed the decoration of a Fe-Ni-based cocatalyst on the surface of the TiO2 photoanode for PEC water splitting. The TiO2 photoanode was hydrothermally synthesized and then decorated by Fe-Ni hydroxide catalyst using photo-assisted electrodeposition. The optimized TiO2/FeNiOOH photoanode exhibited the maximum photocurrent density value of 1.36 mA cm−2, which is almost twice the value obtained for bare TiO2, at 1.23 V vs RHE under the AM 1.5 G illumination. Due to the enhanced light absorption in the UV region, the optimized photoanode exhibited remarkable IPCE and photoconversion efficiency of 87.8% and 0.93%, respectively. Furthermore, excellent faradaic efficiencies of ∼90% for H2 and ∼70% for O2 generations were obtained. Predominantly, the enhancement in the photocurrent potentials was explained in detail. Our study shows the roles and benefits of using bimetallic catalysts with TiO2 photoanodes for sustainable water-splitting applications.